Epithelial downgrowth or epithelialization of the anterior chamber with conjunctival or corneal epithelium is an infrequent although devastating complication of cataract surgery and trauma. Until recently, utilization of better cataract surgical techniques had decreased the incidence of this disorder. However, the increasing use of intraocular lenses has been associated with a resurgence of the incidence of epithelial downgrowth seen at the Department of Ophthalmology, University of Oklahoma. These patients present with a spectrum of symptoms including pain, as well as low grade uveitis, peripheral anterior synechias, angle closure, glaucoma, opacification of the posterior capsule and blindness. Currently available surgical instrumentation and microsurgical approaches to the eye have not afforded adequate salvage of these eyes. This situation has been perpetuated, in part, by the lack of a suitable animal model of epithelial downgrowth from which new surgical techniques can be developed. This study will attempt to develop a cat and subsequent primate model with correlation studies by light, scanning and transmission electron microscopy. A newly developed fiberoptic endoscopic system will be used in conjunction with a vitrectomy instrument, which will afford up to 75X magnification and direct visualization of the epithelial downgrowth patterns, and allow careful and complete excision of these membranes from cornea, angle, iris and ciliary body. If growth of intraocular epithelium in the animal model can be eliminated, we will submit a protocol for trial of these techniques on patients referred with epithelial downgrowth.